过孔激起反谐振对信号传输的影响

Analysis of the effect of the anti-resonance inspired by via on PCB on signal transmission

针对过孔激起的平面谐振对传输线传输效果有着严重影响这一问题,提出了一种能够准确预测平面过孔对传输效果影响的方法.将过孔与平面谐振紧密结合,补充了平面模式阻抗抑制法所没有讨论的情况,通过引入线性网络阻抗Z参数模型,可以准确判断不同位置处,激起相同谐振频率的两过孔传输效果是否优于单一过孔.此外,对多种过孔的传输效果进行了分析.仿真结果表明,当考虑平面谐振对传输效果的影响时,电源地平面间应尽量使用通孔;在多层印刷电路板中的信号线上,当过孔造成信号两次换层时,返回路径仅在离平面边沿最近处改变.

The anti-resonant effect of the plane inspired by the via has a serious impact on the transmissioneffect.To overcome this shortcoming,a novel method,based on the combination of the via and plane resonance,is proposed.The two ports have the same anti-resonant frequency,which don＇t be discussed in suppressing modal impedances.By introducing the impedance parameter Z of the linear network,the new method can accurately predict whether the transmission effect of two vias which have the same anti resonant frequency is better than that of a single via.Different kinds of vias are tested and discussed.Our extensive experiments lead to two useful finding.First,the through via should be employed when the plane＇s antiresonant effects are taken into account.Second,when the signal＇s path alters twice due to vias,the return path just changes at the via nearest to the plane＇s edge.